Knitting machine stop mechanism



1954 D. PERNICK KNITTING MACHINE STOP MECHANISM Filed July 12, 1952 SYNCHR.

MECH.

PRIMARY SECOND/JR! KNOCK-OFF MECHANISM INVENTOR flawd Penna/6 BY Q Q. Mun-4:2,

ATTORN E Patented Feb. 16, 1954 UNITED STATES PATENT OFF ICE KNITTING-MACHINE STJOP. Davidli'ernick, Brooklyn, N. Y.

ApplicationJul'y 12, 1952. Serial-N 0.251850% 12 Claims. 1

Theil presenti invention relates to; knitting marchines: of; thmflatabedrztype; such as tricot. and

raschel machines and the like, and more particu-.-

larly: to: knockeoffi. or? st'opvmechanism; for: such machines.

One ofthe problems in theknittingxoffabricris the: waste-v occasioned. by: defects: in. the fabric. particularly serious. in; connection. with 'knittingimachines of theutricot. typ rwhichthave a very wide bed and are operated at high. speeds, ,becausetone improperly formed-stitch in :azcourse renders-a: wide piecerofi fabric. defective. In the eventimproper; stitch formation. is.-. caused by breakage: of; a. needle: hook;.. which a frequently occurs: at high: speed'. operation; a considerable length: oil fabric. having, imperfections. may be knitted before the operator; detectsthesame and can stop the machine.

Accordingly. an 1 object of the present-invention isto prov-idemeans: for automatically detecting improperrstitch; formationand 1, stopping; the knitting; machine in? the. event thereof.

Another object. is: to detect the absence: of. a stitch. or: loop; :on. the shank of. the needles" ata moment insthe.- knittingcycle' whenv the stitch-or. loop! should vbeon. the-shank.

Another. object isto providemechanism of. the foregoing character-*which-can bereadily incorporatedrinnewly built. machines-.and canalso be installedon. existing machines- I Arfurther; object istoaccomplish the. foregoing. by. providing mechanism. which is simple and economical in. construction, and. is. practical. in operations Other. and further obi ects will be bviousupon annndrstanding. of. the. illustrative embodiment aboutto. be described, or. will. be. indicated inthe appended; claims, and various advantages not' referred. to herein will'occur to one skilled. in the art upon employment of the invention in practi'ce.

. In accordance with the presentin'vention; the foregoingobjects' may be. accompliishedby providing k'nock off" or sto mechanism comprising in combination an electrically operated device" a'dapted to. effect stoppage of the... knitting maliineyan electrically. conductive needle barhav ing conductive needles thereon" and in electrical contact" therewith; 1 switch; elements mounted on thenee'dle bar but electrically insulated'there fiom,;havinga,yieldable. portionin electricalcontacti 'i'tlia. needle. shank at; a zone where. loop ofa stitch .should'be-ldisposed .at aa'nredetenmined-momentlinithe.knittinggciiclel the tact. between-.lthe switch ielementportion and the needleshank; asource of electrical energy for the-device; and meansior establishing: acircuit from the source through the switch element, the needle bar. and the. device, including. alnormally open switch; andmeansfor closing the-switch only. at the predetermined. moment in i the. knit.- ting cycle when. the loops ofv the stitches should break the contact between. the yieldable switch element. portions-and the needle shanks. where.- by, intthe absence: ofonei. or more loopsat such momenhthe device is energized to effectstop, page of. the machine.

A. preferred embodiment-of the invention. has

beenchosen .for. purposes of illustration and :description and isshown in theaccompan-ying drawing,; forming apart otthe; specification,. wherein:

Fig. 1 is an elevational-yiewwhereinaportion of.--a. needlebarand a .pair. of knitting needles. are shownasseenfromthe back of the machine and a switchelement is associated with each. of. the needles.

Fig. 2 isa sideview, partly: in section. andparte 1y in elevation,illustrating; the loop of a: stitch in. a. positiononthe. needle shank to break the contact between the. switch element and the needle.

Fig. 31 is. a view. similar to Fig. 2, illustrating the. stitchinlaposition just priorto breaking the contact and including a wiring diagram whichillustrates the. manner in which the knocksoif mechanismis controlled by. the. switch means as.- sociated. withthe. needle.

Referring to the drawing in. detail ,andmore particularly, toJFigsk 1 andr2tthereof; there. is shown-a portion .oilaneedle support II), which for purposes oflexplaining theinvention' may be. considered a portion. offthe. needle. bar. of. a flatbed knitting machine, anda pair ofneedles: H each having its shank [2f.mo11nted inthesupport. The support. may. beany, of the wellsknown. types utilized. in. connection with such. machines, al.- though the same is shown herein asalead. block having theneedlesshank casttherein. In. event, the .needleand. the support'are electrically conductive and are. in .electricallcontactwithithe needle. bar. proper or. a common conductor. as.- sociatedfwi'tlithe needle bar.

Only two ,needl'esare shown, for. purposes of..il.- Iustration, buti't will'be appreciated. that. b.1111:- dredsoflsuchneedlesare. usuall mountedlonthe needleibar. Also-,..while..the.;needle-shownzheran is.-,0'the typ,e known. assaibeardedgneedl'e, it. will.

pitcsence ofiazonewilll'bl eak'thescombe; understood from the following descriptiorr that the present invention may be practiced in connection with other types of needles including latch needle, plush points and the like.

A switch element M is mounted on the needle support which has a yieldable portion l5 normally in electrical contact with the needle shank at a point or zone where the loop L of a stitch should be disposed at a predetermined moment in the knitting cycle. The yieldable portion preferably has a straight section iii adjacent its upper end which makes contact with the needle shank along a length thereof coextensive with the zone where the loop may be located. Preferably, the yieldable portion causes the section It to engage the needle shank under very light spring tension suificient to establish an electrical connection but without offering undue resistance to the loop, whereby fraying of the yarn does not occur. The free end ll of the yieldable portion extends away from the needle shank to form a Wedge which facilitates positioning the loop between the section it; and the needle shank and further minimizes frictional forces acting on the yarn.

The element Hl may be mounted on the needle support in any suitable manner. For example, a plurality of such elements may have the end opposite the free end in electrical contact with a common conductor which extends lengthwise with the needle bar. As shown in the drawing, each element is secured to a bar H; which is attached to the needle support but is electrically insulated therefrom by a strip 20 of non-conductive material, such as Bakelite or the like. It

will be appreciated that the elements could be stamped from a metallic strip to form a comblike structure wherein all the elements extend like teeth from a continuous strip which serves as the common conductor.

In Fig. 3, the needle and switch element associated therewith is shown in electrical connection with means for effecting stoppage of the knitting machine in the event a loop does not break the contact between the switch element and the needle at the predetermined moment in the knitting cycle. Such means include an electrically operated knock-01f mechanism 25 of any known type, a source of electrical energy, herein shown as a transformer 26, for supplying current at a low voltage, and a normally open switch 21.

As shown, one leg of the secondary of the transformer is connected to one side of the knock-off mechanism 25, the other side of this mechanism is connected to the needle bar It], the switch elements are connected through the conductor Hi to one side of the switch 21, and the other side of the switch is connected to the other secondary leg of the transformer.

In order to establish an electrical circuit and energize the knoclooff mechanism in the event a loop fails to be disposed between the switch element section and the needle shank at the predetermined moment, mechanism is provided for closing the switch 2'! at such moment. Such mechanism includes a cam 29 driven in synchronism with the knitting elements of the machine which has one or more projections 30 thereon for effecting closing of the switch 21 at the exact moment a loop L should be at the desired zone alon the needle shank.

For example, in Fig. 3 the loop shown is just about to be drawn between the switch element section It and the needle shank, and the projection 30 is just about to eiiect. clos n Of t e 4 switch 21. Thus, should the loop break or for any other reason fail to reach the proper zone on the shank, there will be electrical contact between the needle and the switch element and closing of the switch 21 will then complete the knock-off mechanism energizing circuit. Should the loop be properly positioned at the desired moment, as shown in Fig. 2, closing of the switch does not cause the mechanism to be energized because the circuit is open between the needle and the switch element.

While only one needle and switch element have been shown, it will be appreciated that if hundreds of the same are electrically connected in the circuit in the same manner, the failure of any single switch element to be separated from its needle will cause energization of the knock-off mechanism at the predetermined moment. likewise, if all needles have a loop thereon at such moment, which breaks the contact between the needles and the switch elements, the circuit is open when the switch 2'! is closed.

From the foregoing description, it will be seen that the present invention provides a novel and useful arrangement of devices for detectin improper stitch formation and automatically effecting stoppage of the knitting machine instantaneously, whereby very little fabric and yarn are wasted.

As various changes may be made in the form, construction, and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matters are to be interpreted as illustrative and not in any limiting sense.

What is claimed is:

1. In stop mechanism for knitting machines of the class described, the combination of an electrically operated device adapted to efiect stoppage of the machine, an electrically conductive needle bar having a conductive needle thereon in electrical contact therewith, a conductive bar, an insulator interposed between said needle bar and said conductive bar, a switch element having a base portion mounted on said conductive bar and having a yieldable portion in electrical contact with the shank of said needle at a zone where the loop of a stitch is disposed at a predetermined moment in the knitting cycle, whereby the presence of a loop at the Zone will break the contact between said portion and the needle shank, a source of electrical energy for said device, means for establishing a circuit from said source through said switch element, said needle bar, and said device including a normally open switch, and means for closing said switch only at said moment in the knitting cycle when a loop of the stitch should break the contact between said yieldable portion and the needle shank, whereby in the absence of a loop at said moment said device is energized to effect stoppage of the machine.

2. Mechanism according to claim 1, wherein said switch closing means are operated in synchronism with movement of said loop.

3. Mechanism according to claim 1, including a plurality of said needles, a switch element for each needle and means electrically connecting all of said switch elements, whereby said device is adapted to be energized in the absence of a loop on any of said needle shanks.

4. In stop mechanism for knitting machinesof the class described, the combination of an electrically operated device adapted to effect stoppage of the machine, an electrically conductive needle bar having a conductive needle thereon in electrical contact therewith, a conductive bar, an insulator interposed between said needle bar and said conductive bar, a switch element having a base portion mounted on said conductive bar and having a yieldable portion in electrical contact with the shank of said needle, a normally open switch, means for closing said switch at a predetermined moment in the knitting cycle, a source of electrical energy, means for connecting one side of said source to one side of said switch, means for connecting the other side of said switch to said switch element, means for connecting said needle bar to one side of said device, and means for connecting the other side of said device to the other side of said source.

5. In a knitting machine of the class described, the combination of an electrically conductive needle bar, a knitting needle on said bar in electrical contact therewith, switch means including a yieldable portion in electrical contact with the shank of said needle, means for mounting said switch means on said needle bar, and electrically insulating means interposedbetween said switch means and said needle bar.

6. In a knitting machine of the class described, the combination of an electrically conductive needle bar, a plurality of knitting needles on said bar in electrical contact therewith, and switch means including a conductive strip portion extending lengthwise along said bar. an insulating strip between said conductive strip portion and said bar, and including a plurality of yieldable conductive portions each in electrical contact with 6 one of said needles and in electrical connection with said conductive strip portion.

7. Apparatus according to claim 6, wherein said yieldable portions are individually removably connected to said conductive strip portion.

8. In a flat bed knitting machine, the combination of a plurality of needles and a switch element for each of said needles having a portion engaging the shank of a needle and adapted to be moved out of contact therewith by the loop of a stitch on the shank.

9. In a stop mechanism circuit for knitting machines of the class described, the combination of an electrically operated device adapted to effect stoppage of the machine, switch means operable by a loop of a stitch to open the same, a normally open switch, and means for closing said switch at the moment the loop is adapted to open said switch means.

10. In a knitting machine of the class described the combination of a needle having a shank, and a switch element having a portion normally in engagement with said shank at a predetermined zone.

11. In a machine according to claim 10, wherein said element has a straight section contacting said shank at a zone along the length thereof.

12. In a machine according to claim 11, wherein said element has a free end portion which extends away from said shank to provide a wedge.

DAVID PERNICK.

References Cited in the file of this patent UNITED STATES PATENTS Number 

